Intensification and kinetic study of trifluoromethylbenzen nitration with mixed acid in the microreactor

Microreactors are becoming an important tool for rapid exothermic chemical reaction process intensification and continuous flow chemistry. This work focuses on the process intensification and kinetics of the trifluoromethylbenzen nitration in microreactors. The reaction of trifluoromethylbenzene with mixed acid is a typical liquid-liquid heterogeneous reaction, so the mass transfer is the rate-determining step. Two strategies of microreaction systems were established to enhance mass transfer, respectively. Firstly, a scheme for intensifying the nitration reaction process in a capillary microreactor was proposed. The results showed that the conversion was low and could not achieve the expected results. Finally, a Heart-type micromixer with barriers was used to improve the mixing and mass transfer performance. The effects of molar ratio, temperature, sulfuric acid concentration, flow rate, and residence time on the conversion were investigated. The results showed that the residence time was significantly reduced from 4 hours in the batch reactor to 30 s in the Heart-type micromixer. The volume mass transfer coefficient and space-time yield were up to 0.031 s−1 and 16053.55 g·cm−3·h−1, respectively. Meanwhile, to better understand and control the nitration reaction process, the kinetics of the nitration of trifluoromethylbenzene was reported for the first time in a capillary microreactor, and all kinetic data were obtained.